The present invention relates to a programmable thermostat incorporating an interactive liquid crystal display (LCD), and, more particularly, to such a thermostat which includes a feature for providing a running total for the cost of energy consumed during a given period for heating and/or cooling a conditioned space.
Thermostats have been used for many years as temperature sensitive switches which control heating and/or cooling equipment for conditioning a space in which the thermostat, or a temperature sensor connected to the thermostat, is placed. In the well known manner, a simple thermostat can be adjusted to establish a temperature set point such that, when the temperature in the conditioned space reaches the set point, the thermostat interacts with the heating and/or/cooling equipment to take suitable action to heat or cool the conditioned space as may be appropriate for the season as established by a user.
Modern thermostat systems, which take advantage of the ongoing rapid advances in electronic technology and circuit integration, have many features which provide more precise supervision of the heating and/or cooling equipment to achieve more economical and more comfortable management of the temperature of a conditioned space. Many modern thermostat systems include a real time clock, a memory and a data processor to run a process control program stored in the memory; Such thermostats accurately measure the temperature of a temperature sensor disposed in the conditioned space and make decisions to send control signals to the heating and/or cooling equipment in order to closely control the temperature of the conditioned space. The use of programmed thermostat systems permits anticipating and minimizing hysterisis or overshoot of the temperature in the conditioned space. In addition, the program can specify different set points at different times of the day and week and may also include a xe2x80x9cvacationxe2x80x9d mode which employs different set points when the conditioned space is not occupied for an extended period.
Many modern thermostat systems are programmable by a user. Typically, prior art programmable thermostat systems employ a set of fixed position, button-actuated switches to be depressed in a precise sequence to program set points (which may vary with the day of the week) for programmable time periods which may include a vacation mode. The programming sequence may be followed on a separate display, typically an LCD with segmented text characters. In some modern thermostats, xe2x80x9cvirtualxe2x80x9d buttons are presented on the LCD itself which is juxtaposed with a touch pad to effect an interactive touch screen.
Outside of the art of programmable thermostat systems and programmable thermostats, dot matrix LCDs, which have pixel display elements arranged in rows and columns, are widely used. Dot matrix LCDs are not common as user-visible displays on programmable thermostats for viewing alphanumeric and iconic graphic information although such a thermostat is disclosed in, and particular features claimed in, co-pending U.S. patent application Ser. No. 10/440,474, filed May 15, 2003, and entitled: xe2x80x9cReverse Images in a Dot Matrix LCD for an Environmental Control Devicexe2x80x9d by Howard B. Rosen, incorporated by reference herein.
This limited use of dot matrix LCDs in programmable thermostats is because of basic engineering and practical considerations. Displayed information for a programmable thermostat generally includes such things as environmental conditions, heating and/or cooling equipment operation or non-operation, operational modes of the thermostat and the like. The most important information in thermostat displays is capable of being formed from segmented alphanumeric characters on less expensive LCDs without dot matrix capability and with reduced requirements for memory and programming.
Thus, dot matrix LCDs have not been widely used in prior art user programmable thermostats through a failure to understand an extended functionality capability of those devices when dot matrix LCDs are employed with a touch pad to effect an interactive display. This extended functionality is exploited to advantage in the present invention both to greatly simplify user programming and to relieve the manufacturer of the necessity to fabricate variants of the thermostat to suit the control and display aspects of various heating and/or cooling environments.
While the present invention may be practiced using segmented LCDs, it is preferably embodied using dot matrix LCDs.
It is therefore a broad object of this invention to provide a field programmable thermostat which may be user-configured to display ongoing costs of system operation.
It is a more specific object of this invention to provide a programmable thermostat having a touch screen in which the power consumption of each heating/cooling component and the energy costs in the locality are entered by a user in order that the thermostat""s control program can, upon demand, calculate and display the heating/cooling costs accrued beginning with a user-specified starting date.
Briefly, these and other objects of the invention are provided by a programmable thermostat system for controlling space conditioning equipment and which includes: a transparent touch pad juxtaposed with an LCD (preferably dot matrix) to constitute a touch screen for interactive interface with a user; one or more environmental condition sensors for providing an electrical signal indicative of the one or more sensed environmental conditions of a conditioned space; and a processor including: a central processing unit, a real time clock, a memory coupled to the central processing unit for storing program and data information and an input/output unit coupled between the processor and the touch screen for carrying out information transfer therebetween.
A program stored in the memory directs the central processing unit to communicate through the input/output unit to selectively: establish on the LCD a representation of at least one virtual button at a predetermined XY position; read the same XY position on the touch pad to determine if the virtual button has been touched; and if the virtual button has been touched, perform a predetermined action such as moving to a different menu and/or changing operating criteria. An alphanumeric message explaining the function of the virtual button is also displayed, and icon indicators may be employed to unmistakably associate a message with a virtual button. Different menus can place the virtual buttons and messages in various positions on the touch screen to facilitate intuitive programming.
In accordance with the present invention, data about energy utility usage of environmental conditioning equipment connected for control by the thermostat is accumulated for selective display of cumulative energy usage and costs. Preliminarily, a user enters the power consumption rating for each component in the heating and/or cooling system and also the energy cost rates for the applicable utilities in the locality. During normal operation, the thermostat control program records the cumulative time each component operates. Upon an inquiry by the user, the cumulative time each system component has been in operation is used in a calculation with its energy requirement and cost factor to determine and display the current cumulative cost of operating each of the components and their summation of the period. For example, this xe2x80x9cenergy watchxe2x80x9d function can be reset each month. Thus, the user can understand the cost factors in operating the system and make suitable decisions in temperature set points, etc., to minimize the cost of heating and/or cooling the conditioned space.